CN107091294B

CN107091294B - Shock absorber with check disc for orifice passage

Info

Publication number: CN107091294B
Application number: CN201710077365.8A
Authority: CN
Inventors: 查德·拉梅尔
Original assignee: Tenneco Automotive Operating Co Inc
Current assignee: Tenneco Automotive Operating Co Inc
Priority date: 2016-02-18
Filing date: 2017-02-14
Publication date: 2020-06-12
Anticipated expiration: 2037-02-14
Also published as: DE102017101840A1; US9845839B2; CN107091294A; US20170241502A1

Abstract

A shock absorber for a vehicle includes a pressure tube defining a fluid chamber and a piston disposed within the fluid chamber. The piston divides the fluid chamber into an upper working chamber and a lower working chamber and defines a compression passage and a rebound passage. A valve disc assembly of the shock absorber engages the piston and controls fluid flow between the upper and lower working chambers. The valve disc assembly includes a check disc and an orifice disc. The check disc is disposed between the piston and the orifice disc. The orifice disc defines an orifice, and the check disc prevents fluid flow through the orifice when fluid flows in a first direction and allows fluid flow through the orifice when fluid flows in a second direction opposite the first direction.

Description

Shock absorber with check disc for orifice passage

Technical Field

The present disclosure relates to shock absorbers. More specifically, the present disclosure relates to a valve disc assembly for controlling the damping characteristics of a shock absorber during low hydraulic fluid flow.

Background

This section provides background information related to the present disclosure that is not necessarily prior art.

Shock absorbers are used in conjunction with automotive suspension systems to absorb unwanted vibrations which occur during driving. To absorb unwanted vibrations, a plurality of shock absorbers are generally connected between the sprung portion (body) and the unsprung portion (suspension) of the automobile. The piston is located within a pressure tube of the shock absorber and the pressure tube is connected to the unsprung portion of the vehicle. The piston is connected to the sprung portion of the vehicle by a piston rod that extends through the pressure tube.

The piston divides the pressure tube into an upper working chamber and a lower working chamber, both filled with hydraulic fluid. Because the piston is able to restrict the flow of hydraulic fluid between the upper and lower working chambers by valving (biasing) when the shock absorber is compressed or extended, the shock absorber is able to generate a damping force that counteracts the vibrations that would otherwise be transmitted from the unsprung portion to the sprung portion of the vehicle. In a dual tube shock absorber, a fluid reservoir or reserve chamber is defined between the pressure tube and a reserve tube. A base valve is positioned between the lower working chamber and the reserve chamber to control fluid flow between the lower working chamber and the reserve chamber.

For a full displacement valving system, all of the rebound damping forces generated by the shock absorber are the result of piston valving, while the compression forces are a combination of piston and cylinder end valving. The greater the degree to which the piston and/or cylinder end restricts the flow of fluid within the shock absorber, the greater the damping force generated by the shock absorber. Thus, a highly restricted fluid flow will produce a firm ride (firm ride), while a less restricted fluid flow will produce a soft ride (soft ride).

Shock absorbers have been developed to provide different damping characteristics depending on the velocity or acceleration of the piston within the pressure tube. Due to the exponential relationship between the pressure drop and the flow rate of the fixed orifice, achieving a damping force at relatively low piston velocities (i.e., low hydraulic fluid velocities) is a difficult task, particularly at velocities near zero. Low speed damping forces are important for vehicle handling because most vehicle handling events are controlled by low vehicle body speeds.

Various systems for adjusting a shock absorber during low speed movement of a piston include fixed low speed orifice(s) that provide a defined leakage path that is open through the piston for both compression and rebound. While a soft ride is generally preferred during compression, a firm ride is generally preferred during rebound.

Disclosure of Invention

This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features. The present disclosure relates to a shock absorber for a vehicle. The shock absorber may include a pressure tube, a piston, and a valve disc assembly. The pressure tube defines a fluid chamber, and the piston divides the fluid chamber into an upper working chamber and a lower working chamber. The piston defines a compression passage and a rebound passage extending through the piston between the upper working chamber and the lower working chamber.

The valve disc assembly engages the piston and controls the flow of fluid between the upper working chamber and the lower working chamber. The valve disc assembly includes a check disc positioned within the land of the piston and an orifice disc positioned at the land of the piston. The check disc is positioned between the piston and the orifice disc. The orifice disc defines an orifice, and the check disc may control fluid flow through the orifice to allow fluid flow through the orifice in a first direction and to prevent fluid flow through the orifice in a second direction opposite the first direction.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic representation of a typical automobile incorporating at least one shock absorber;

FIG. 2 is a side view, partially in section, of the shock absorber;

FIG. 3 is an enlarged cross-sectional view of the piston assembly of the shock absorber;

FIGS. 4A and 4B are enlarged views of a rebound valve disc assembly and a compression valve disc assembly, respectively; and is

FIG. 5 is an exploded view of the compression valve disc assembly.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

Detailed Description

The present disclosure will now be described more fully with reference to the accompanying drawings. FIG. 1 illustrates a vehicle 10 incorporating a suspension system with shock absorbers having check discs for controlling fluid flow through orifice passages in accordance with the present disclosure. Vehicle 10 includes a rear suspension 12, a front suspension 14, and a body 16. Rear suspension 12 has a transversely extending rear axle assembly (not shown) adapted to operatively support the rear wheels 18 of the vehicle. The rear axle assembly is operatively connected to body 16 by means of a pair of shock absorbers 20 and a pair of helical coil springs 22. Similarly, front suspension 14 includes a transversely extending front axle assembly (not shown) that operatively supports front wheels 24 of the vehicle. The front axle assembly is operatively connected to body 16 by means of a second pair of shock absorbers 26 and by a pair of helical coil springs 28.

These shock absorbers 20 and 26 serve to attenuate the relative movement of the unsprung portion (i.e., front and rear suspensions 12 and 14, respectively) and the sprung portion (i.e., body 16) of vehicle 10. While vehicle 10 is depicted as a passenger vehicle having a front axle assembly and a rear axle assembly,

shock absorbers

20 and 26 may be used with other types of vehicles or in other types of applications including, but not limited to, vehicles employing independent front and/or independent rear suspension systems.

Referring now to FIG. 2, shock absorber 20 is shown in greater detail. While FIG. 2 only illustrates shock absorber 20, it is to be understood that shock absorber 26 comprises the same components as shock absorber 20. Shock absorber 26 only differs from shock absorber 20 in the manner in which it is adapted to be connected to the sprung and unsprung masses of vehicle 10. Further, while shock absorber 20 is depicted as a dual tube shock absorber, shock absorber 20 could also be a single tube shock absorber.

Shock absorber 20 comprises a pressure tube 30, a piston assembly 32, a piston rod 34, a reserve tube 36 and a base valve assembly 38. Pressure tube 30 defines a working chamber 42. Piston assembly 32 is slidably disposed within pressure tube 30 and divides working chamber 42 into an upper working chamber 44 and a lower working chamber 46. As seen in fig. 3, a seal 48 is disposed between piston assembly 32 and pressure tube 30 to permit sliding movement of piston assembly 32 with respect to pressure tube 30 without generating undue frictional forces as well as sealing upper working chamber 44 from lower working chamber 46.

Piston rod 34 is attached to piston assembly 32 and extends through upper working chamber 44 and through an upper end cap 50 which closes the upper end of pressure tube 30. The end of piston rod 34 opposite piston assembly 32 is adapted to be secured to the sprung portion of vehicle 10.

Valving within piston assembly 32 controls the movement of fluid between upper working chamber 44 and lower working chamber 46 during movement of piston assembly 32 within pressure tube 30. Because piston rod 34 extends only through upper working chamber 44 and not lower working chamber 46, movement of piston assembly 32 with respect to pressure tube 30 will result in a difference in the amount of fluid displaced in upper working chamber 44 and the amount of fluid displaced in lower working chamber 46. The differential amount of displaced fluid flows through base valve assembly 38, piston assembly 32, or a combination thereof.

Reserve tube 36 surrounds pressure tube 30 to define a fluid reserve chamber 52 located between tubes 30 and 36. Base valve assembly 38 is disposed between lower working chamber 46 and reserve chamber 52 to control the flow of fluid between

chambers

46 and 52. As shock absorber 20 extends in length, fluid will flow from reserve chamber 52 through base valve assembly 38 to lower working chamber 46. Fluid may also flow from upper working chamber 44 to lower working chamber 46 through piston assembly 98. When shock absorber 20 compresses in length, excess fluid must be removed from lower working chamber 46. Thus, fluid flows from lower working chamber 46 through base valve assembly 38 to reserve chamber 52. Additionally, fluid also flows from lower working chamber 46 to upper working chamber 44 through piston assembly 98.

Referring now to FIG. 3, piston assembly 32 includes a piston body 60, a compression valve assembly 62, and a rebound valve assembly 64. Piston body 60 defines a plurality of compression fluid passages 66 and a plurality of rebound fluid passages 68 and includes a compression valve land 70 and a rebound valve land 72. The compressed fluid passage 66 includes an inlet 74 and an outlet 76. Rebound fluid passage 68 includes an inlet 78 and an outlet 80. Compression fluid passage 66 and rebound fluid passage 68 fluidly couple upper working chamber 44 and lower working chamber 46.

Piston body 60 abuts compression valve assembly 62 which abuts a shoulder 82 formed on piston rod 34. Piston body 60 also abuts rebound valve assembly 64, which is retained by retaining nut 84. Retaining nut 84 secures piston body 60 and valve assemblies 62 and 64 to piston rod 34.

Compression valve assembly 62 includes retainer 90, one or more spacers 92, and valve disc assembly 94. Retainer 90 is disposed above piston body 60 and abuts shoulder 82. A spacer 92 may be disposed between valve disc assembly 94 and retainer 90. The valve disc assembly 94 abuts the compression valve land 70 and closes the outlet 76 of the compression fluid passage 66.

Rebound valve assembly 64 comprises a retainer 100, one or more spacers 102, and a valve disc assembly 104. Retainer 100 is disposed below piston body 60 and abuts retaining nut 84. Spacers 102 may be disposed between valve disc assembly 104 and retaining nut 84 and between valve disc assembly 104 and piston body 60. Valve disc assembly 104 abuts rebound valve land 72 and closes outlet 80 of rebound fluid passages 68.

The damping characteristics for both rebound (extension) and compression of shock absorber 20 are determined by piston assembly 32. More specifically, the piston assembly 32 is provided as a full-flow piston assembly that includes valving of medium/high fluid speeds and independent valving of low piston speeds (i.e., low hydraulic fluid flow or low fluid speed). At mid/high levels of velocity, damping is controlled by the deflection of valve disc assembly 94 of compression valve assembly 62 and valve disc assembly 104 of rebound valve assembly 64. At low horizontal speeds, damping is controlled by the bleed passage. In the following, valve disc assembly 94 for compression valve assembly 62 is referred to as compression valve disc assembly 94 and valve disc assembly 104 for rebound valve assembly 64 is referred to as rebound valve disc assembly 104.

Fluid flow through compression fluid passage 66 is controlled by compression valve assembly 62. During a compression stroke, the pressure of the fluid in lower working chamber 46 increases and the pressure of the fluid in upper working chamber 44 decreases, thereby allowing fluid to flow from lower working chamber 46 to compression fluid passage 66. Fluid pressure within compression fluid passage 66 eventually opens compression valve assembly 62 by deflecting compression valve disc assembly 94. Thus, fluid flows through the compression fluid passages 66 into the upper working chamber 44. As described herein, prior to deflection of compression valve disc assembly 94, a controlled amount of fluid flows from lower working chamber 46 to upper working chamber 44 through the fixed orifice bleed passage, which provides damping at low fluid velocities.

Fluid flow through rebound fluid passages 68 is controlled by rebound valve assembly 64. During a compression stroke, rebound valve assembly 64 restricts fluid flow through rebound fluid passages 68. Fluid in lower working chamber 46 exerts a force on rebound valve assembly 64. Rebound valve assembly 64 seals rebound valve land 72 of piston body 60 preventing fluid from entering rebound fluid passages 68 from lower working chamber 46 at medium/high fluid velocities.

During a rebound stroke, fluid in upper working chamber 44 is pressurized and fluid flows from upper working chamber 44 to rebound fluid passages 68. Fluid pressure within rebound fluid passages 68 ultimately opens rebound valve assembly 64 by deflecting rebound valve disc assembly 104. Thus, fluid flows through rebound fluid passages 68 into lower working chamber 46.

During a rebound stroke, compression valve assembly 62 restricts fluid flow through compression fluid passage 66. Specifically, fluid in upper working chamber 44 exerts a force on compression valve assembly 62. Compression valve assembly 62 seals against compression valve land 70 of piston body 60 to prevent fluid flow through compression fluid passage 66. As described herein, prior to deflection of rebound valve disc assembly 104, a controlled amount of fluid flows between lower working chamber 46 and upper working chamber 44 through a bleed passage that provides damping at low fluid velocities.

Referring now to fig. 4A and 4B, rebound valve disc assembly 104 and compression valve disc assembly 94 comprise a plurality of discs that control the flow of fluid through piston body 60. As shown in FIG. 4A, rebound valve disc assembly 104 comprises an orifice disc 150 and one or

more spring discs

152 and 154. The orifice disc 150 defines one or more orifices 156 and may also be referred to as a bleed disc.

Spring discs

152 and 154 are positioned next to the orifice disc 150. More specifically, the order of the discs from the rebound valve land 72 toward the retainer 100 is provided as an orifice disc 150,

spring discs

152 and 154.

Orifice disc 150, and

spring discs

152 and 154 are positioned at rebound valve land 72 of piston body 60. Orifice disc 150 abuts rebound valve land 72 and forms a bleed passage, represented by arrow 160, that allows fluid to flow between upper working chamber 44 and lower working chamber 46 at low piston speeds. Bleed passage 160 is open during compression and rebound thereby allowing fluid flow from upper working chamber 44 to lower working chamber 46 and vice versa.

Referring to fig. 4B and 5, compression valve disc assembly 94 includes a check disc 162, an intermediate disc 164, an orifice disc 166 and one or

more spring discs

168 and 170. Check disc 162 is positioned within compression valve land 70 and on piston body 60. Orifice disc 166 is positioned at compression valve land 70 with intermediate disc 164 positioned between orifice disc 166 and check disc 162.

Spring discs

168 and 170 are positioned on the opposite side of the orifice disc 166 from the intermediate disc 164.

Check disc 162 defines one or more passages 172 for allowing fluid flow during low piston speeds, as described below. Channel 172 is configured to abut a surface of piston body 60 and not overlap with

passages

66 and 68 defined by piston body 60. The number, size, and shape of the passages may be configured based on, for example, the piston, other discs of the valve disc assembly, and/or desired damping characteristics. Thus, the channel is not limited to the illustrated shape.

Intermediate disc 164 has a smaller diameter than check disc 162 and orifice disc 166. The diameter of the intermediate disk 164 is configured so as not to overlap or obstruct the passage 172. Intermediate disc 164 defines a gap between check disc 162 and orifice disc 166 to provide space for check disc 162 to flex during compression. The intermediate disc 164 may also provide a preload on the remainder of the valve disc assembly 94.

The orifice disk 166 abuts the compression valve land 70 and defines one or more orifices 174. Orifice disc 166 forms a bleed passage, represented by arrow 176 (fig. 4B), with channel 172 of check disc 162. Bleed

passages

176 and 160 control the damping characteristics of the shock absorber during low fluid speeds by allowing a limited amount of fluid to flow between upper and lower working chambers 44 and 46. Unlike the bleed passage 160, which is open during compression and rebound, the bleed passage 176 is open during compression, but closed during rebound.

More specifically, check disc 162 controls fluid flow between upper working chamber 44 and lower working chamber 46 during low piston speeds via bleed passage 176. At low piston speeds during compression, fluid from lower working chamber 46 flows through compression passages 66. Check disc 162 flexes to allow fluid to flow through passage 172 and out through orifice 174 of orifice disc 166 to upper working chamber 44. At low piston speeds during rebound, fluid from upper working chamber 44 flows toward compression passages 66. Pressure from the fluid pushes check disc 162 against piston body 60 such that channel 172 seals against piston body 60. Thus, during low piston speeds, fluid is prevented from flowing through bleed passage 176 and into compression passage 66.

Check disc 162 of the present disclosure controls bleed passage 176 formed by aperture 174 of aperture disc 166 and channel 172 of check disc 162 such that bleed passage 176 is closed during rebound and bleed passage 176 is open during compression. Thus, the

bleed passages

160 and 176 provide damping at low fluid speeds during compression, and the bleed passage 160 provides damping at low fluid speeds during rebound. By having check disc 162, these

shock absorbers

20, 26 provide soft damping characteristics for low speed compression and firm damping characteristics for low speed rebound. Thus, for low fluid velocities, the damping characteristics for

shock absorbers

20, 26 may be independently adjusted for rebound and compression. In the exemplary embodiment, check disc 162 is disposed with compression valve disc assembly 94. It will be readily appreciated that check disc 162 may be disposed in rebound valve disc assembly 104 for controlling the bleed passage on the rebound side such that the bleed passage will allow fluid flow during rebound and prevent fluid flow during compression.

The foregoing description of the embodiments has been presented for purposes of illustration and description. These descriptions are not intended to be exhaustive or to limit the disclosure. Individual elements and features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable as applicable and can be used in even selected embodiments not explicitly shown or described. It can also be varied in a number of ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

The exemplary embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

When an element or layer is referred to as being "on" … …, being "engaged to," "connected to," or "coupled to" another element or layer, it can be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on … …", "directly engaged to", "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between such elements should be interpreted in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Spatially relative terms, such as "inner," "outer," "below," "lower," "above," "upper," and the like, are used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device is turned over in the figures, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Claims

1. A shock absorber for a vehicle comprising:

a pressure tube defining a fluid chamber;

a piston disposed within the fluid chamber, the piston dividing the fluid chamber into an upper working chamber and a lower working chamber, wherein the piston defines a compression passage and a rebound passage extending through the piston between the upper working chamber and the lower working chamber; and

a valve disc assembly engaging the piston and controlling fluid flow between the upper working chamber and the lower working chamber, the valve disc assembly comprising a check disc positioned within the land of the piston and an orifice disc positioned at the land of the piston, wherein

The orifice disk defines an orifice, and

the check disc defines one or more passages and is positioned between the piston and the orifice disc, the check disc controlling fluid flow through the orifice by compressing from a seated position to an unseated position on the piston to allow fluid flow through the orifice in a first direction and prevent fluid flow through the orifice in a second direction opposite the first direction when the check disc is in the seated position, the shock absorber further comprising an intermediate disc positioned between the orifice disc and the check disc, wherein an outer diameter of the intermediate disc is less than an outer diameter of the orifice disc and an outer diameter of the check disc.

2. The shock absorber of claim 1, wherein the passages are defined along a portion of the check disc adjacent the surface of the piston and distal the compression passage and the rebound passage.

3. The shock absorber of claim 1 wherein the check disc defines one or more passages positioned outboard of the portion of the check disc that overlaps the intermediate disc.

4. The shock absorber of claim 1 wherein the valve disc assembly controls fluid flow on the compression side of the piston.

5. A shock absorber for a vehicle comprising:

a pressure tube defining a fluid chamber;

a piston disposed within the fluid chamber and having a support land extending circumferentially along a surface of the piston, wherein the piston divides the fluid chamber into an upper working chamber and a lower working chamber, and the piston defines a compression passage and a rebound passage extending through the piston between the upper working chamber and the lower working chamber; and

a valve disc assembly engaging the piston and controlling fluid flow between the upper working chamber and the lower working chamber, the valve disc assembly comprising a check disc, an intermediate disc, and an orifice disc, wherein:

the check disc is positioned within the seating surface of the piston and defines a passage,

the intermediate disc being positioned between the check disc and the orifice disc, the intermediate disc having an outer diameter less than the outer diameter of the orifice disc and the outer diameter of the check disc,

the orifice disc defines an orifice, the orifice and the passage of the check disc form part of a bleed passage between the upper working chamber and the lower working chamber, and

the check disc closes the bleed passage when fluid flows in a first direction and opens the bleed passage when fluid flows in a second direction opposite the first direction.

6. The shock absorber of claim 5 wherein in the first direction fluid flows from the upper working chamber toward the lower working chamber and in the second direction fluid flows from the lower working chamber toward the upper working chamber.

7. The shock absorber of claim 5 wherein the valve disc assembly controls the flow of fluid through the compression passage.

8. The shock absorber of claim 5 wherein the orifice disc is positioned on the support table.

9. The shock absorber of claim 5, wherein the check disc presses against a surface of the piston when fluid flows in the first direction and moves away from the piston when fluid flows in a second direction.

10. The shock absorber of claim 5 wherein the passage of the check disc is provided at a location of the check disc that overlaps a surface of the piston distal from the compression passage and is outside of the outer diameter of the intermediate disc.

11. The shock absorber of claim 5 wherein the intermediate disc defines a gap between the check disc and the orifice disc.

12. A shock absorber for a vehicle comprising:

a pressure tube defining a fluid chamber;

a piston disposed within the fluid chamber, the piston dividing the fluid chamber into an upper working chamber and a lower working chamber, wherein the piston defines a compression passage and a rebound passage extending through the piston between the upper working chamber and the lower working chamber;

a rebound valve assembly engaging the piston and controlling fluid flow through the rebound passage; and

a compression valve assembly engaged with the piston, the compression valve assembly controlling fluid flow through the compression passage, wherein the compression valve assembly includes a check disc and an orifice disc defining a gap therebetween, the orifice disc defining an orifice, the check disc positioned between the piston and the orifice disc, and the check disc controlling fluid flow through the orifice, wherein the check disc prevents fluid flow through the orifice during a rebound stroke and allows fluid flow through the orifice during a compression stroke.

13. The shock absorber according to claim 12, wherein:

the piston includes a support land extending circumferentially along a surface of the piston,

the check disc is positioned within the support land, and

the orifice disc is positioned at the support table.

14. The shock absorber of claim 12, wherein a portion of the check disc along a surface of the check disc adjacent the piston and away from the compression passage and the rebound passage defines one or more channels.

15. The shock absorber according to claim 12, further comprising:

an intermediate disc positioned between the orifice disc and the check disc and defining a gap between the orifice disc and the check disc, wherein an outer diameter of the intermediate disc is less than an outer diameter of the orifice disc and an outer diameter of the check disc.

16. The shock absorber according to claim 12, further comprising:

an intermediate disk positioned between the orifice disk and the check disk, wherein an outer diameter of the intermediate disk is less than an outer diameter of the orifice disk and an outer diameter of the check disk, and further wherein,

the check disc defines one or more channels at a location of the check disc that overlaps a surface of the piston distal from the compression passage and is outside of an outer diameter of the intermediate disc.